The invention is directed to a container for the transportation and/or storage of radioactive materials which emit .gamma.- and n-radiation and produce noteworthy residual heat consisting of a container body having a shielding function for .gamma.- and n-radiation and an inner cover.
Container which are employed for the transportation and/or storage of spent fuel elements must safely confine the radioactivity of the inserted goods and prove in rigorous tests that this is also guaranteed in extreme accident situations. However, simultaneously they must also shield off the gamma and neutron rays set free in the radioactive decay reactions and lead off the heat of decay to the outside. The shielding function must be substantially maintained even after accident caused stresses.
Known shielding containers for the most part consist of a metallic base container and which have the necessary wall strength for the shielding of the gamma rays, customarily made of steel or a combination of lead and steel, and an outer shell of neutron shielding material with a high portion of water or in the form of a water jacket.
The disadvantage in these constructions is that even slight collisions of the containers, as can occur even in routine operation, can lead to damage of the neutron shielding and then make necessary an expensive, total repair of the entire container. In a severe accident, characterized by high impact strength and the action of fire this neutron shielding can fail to work and increase the dosage attained in the environment of the container.
While the metallic .gamma.-shielding wall is preserved according to experience in severe accidents, the outer laying neutron shielding fails because of the mechanical and thermal influences with the result of a corresponding increase of the neutron loading of the environment.
Therefore it was the problem of the present invention to develop a container for the transportation and/or storage of radioactive materials, especially for irradiated nuclear fuel elements and highly active waste consisting of a base body having a shielding function for .gamma.- and n-radiation and an inner coating of corrosion resistant material which has a further n-shielding stable to the effects of the external accidents in order to still maintain sufficient shielding effect in the event of the loss of the external shielding. This additional shielding action, however, should not prevent the drawing off of the heat of decay from the inner space of the container.